-- Per-user chat preferences.
--
-- A row is created on first change, so absence means "all defaults". That is
-- why every column carries the product default rather than something neutral:
-- reading a missing row and reading an untouched row must give the same answer.
CREATE TABLE IF NOT EXISTS chat_settings (
    user_id                UUID        PRIMARY KEY REFERENCES users(id) ON DELETE CASCADE,

    -- Read receipts are reciprocal: turning them off also stops you seeing
    -- other people's. Enforced in the service, not here.
    read_receipts          BOOLEAN     NOT NULL DEFAULT TRUE,

    -- Who may START a conversation with this user:
    --   anyone      — no restriction (default)
    --   friends     — people they follow, or who follow them, accepted
    --   account_age — accounts at least min_account_age_months old
    --   same_gender — accounts whose gender matches theirs; requires the user
    --                 to have set their own gender, since there is nothing to
    --                 match against otherwise
    who_can_message        VARCHAR(16) NOT NULL DEFAULT 'anyone',

    -- Only meaningful when who_can_message = 'account_age'.
    min_account_age_months INTEGER     NOT NULL DEFAULT 3,

    -- Consent for using this user's chats as training data for the Kautilya
    -- assistant. Recorded now so the choice exists before the feature does —
    -- collecting consent retroactively is worse than collecting it early.
    train_kautilya         BOOLEAN     NOT NULL DEFAULT TRUE,

    created_at             TIMESTAMPTZ NOT NULL DEFAULT now(),
    updated_at             TIMESTAMPTZ NOT NULL DEFAULT now(),

    CONSTRAINT chat_settings_who_can_message_check
        CHECK (who_can_message IN ('anyone', 'friends', 'account_age', 'same_gender')),
    CONSTRAINT chat_settings_account_age_check
        CHECK (min_account_age_months BETWEEN 1 AND 120)
);